Production of vinyl cyanide



Patented Get. 23, 1947 sTArEs FATE orrlce' ,7 2,429,459 PRODUCTION orVINYL cramps Charles R. Harris, Lockport, N. Y assig'nor to E. '1. dinPout de Nemours & Company, Wilmington, Del, a corporation of Delaware NoDrawing Application April 19, 1946,

Serial No. 663,604 (cl. 260-464) 4 Claims. 1

formed in good yield by the following reaction:

The reaction is endothermic.

This application is a continuation-in-part of my copending applicationSerial No. 518,013, filed January 12, 1944. I

In a preferred mode of practicing my invention, succinonitrile is heatedto form vapor which is passed through a heated reactor or passed overany suitable heated surfacein the presence solely of inert material. Byinert material is, of course, meant material which is catalyticallyinactive and which is inert to reactants and reaction products. Suchmaterial includes, for example, glass, porcelain, stainless steel, andthe like.

The process of the present invention may be carried out'at a temperaturewithin the range 300-700 C., with particularly high yields to beobtained at a temperature between 500 C, and 650 C. Some formation ofvinyl cyanide will occur when the succinonitrile is pyrolyzed at atemperature as low as 300 C., but below this temperature the yieldbecomes too low to be of commercial importance. I prefer not to exceed atemperature of about 700 C. to avoid excessive, undesired decompositionreactions.

I prefer to carry out the reaction in the presbeads.

glass beads rested on the Raschig rings. A thermocouple was provided formeasuring the temperature between the Raschig rings and the glass When adehydrocyanating catalyst is used, it is placed between the Raschigrings and glass beads. A catalyst was used for comparison of results asset forth below.

In operation, the tube was heated to an inside temperature of 300 C. to700 C., and a slow ence of an inert diluent gas such as hydrogen ornitrogen. Such gas may be mixed with succinonitrile vapors and thevapor-gas mixture subjected to the pyrolyzing temperature, or the gasmay be separately introduced into the reaction space. The amount ofdiluent gas may be varied over a wide range, e. g., from 10% to 90% byvolume of the vapor-gas mixture. Ordinarily, a mixture of about 50%diluent gas is preferred. The following example further illustrates myinvention:

Ezmnple A vertical, stainless steel tube provided with an inlet at thetop and an outlet at the bottom was arranged to be heated in an electricfurnace. A layer of small porcelain Raschig rings was placed in thebottom of the tube upon which was placed a three-inch layer (75 cc.) ofglass beads. The

stream of molten succinonitrile was introduced in the top of the tubeonto the glass beads. The succinonitrile was rapidly vaporized oncontact with the hot glass beads, and the vapors were immediatelysubjected to the pyrolyzing temperature. The succinonitrile vapors werediluted with hydrogen which was introduced in the top of the reactiontube, above the glass beads. This example shows comparative results withsimilar pyrolysis carried out in the presence of'the followingdehydrocyanating catalysts:

Run Catalyst A 300 cc. of alumina pellets. 3 300 cc. of alumina pelletsimpregnated with 10% by weigh; of a 50-50 mixture of sodium andpotassium cy e. C cc. of 4-8 mesh size wood charcoal impregnated withabout 15% by weight 0! a 50-50 mixture of sodium and potassium cyamdes.

. 12.5 cc. 0! the catalyst 0! Run 0.

75 cc. of wood charcoal, 4-8 mesh size.

none.

none.

cc. of the catalyst of Run 0.

The following results were obtained:

Reference in the specification and claims to parts, proportions, andpercentages, unless other wise specified, refers to parts, proportions,and percentages by weight.

Since it is obvious that many changes and modiflcations can be made inthe above-described details without departing from the nature and spiritof the invention, it is to be understood that the invention is not to belimited to said details ex- 3. A process for the production or vinylcyanide which comprises subjecting succinonitrile vapor together with aninert gas to pyrolysis at a temperature of 500 C. to 650 C. in thepresence sole- 1 2,205,239

1y of inert material.

5 of inert material.

4. A process for the production of vinyl cyanide which comprisessubjecting auccinonitrile vapor 1 together with hydrogen to pyrolysis ata temperature of 500 C. to 650 C. in the presence solely CHARLES R.HARRIS;

REFERENCES orrnn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,407,848 Ray Sept. 17, 1946Carter et a1 June 18, 1940

